In various industries, items are sold in batches satisfying various constraints. As an example, items of non-uniform size, shape or weight, e.g. food items such as meat, fish, fruit and vegetables, are typically handled and delivered to customers in batches having a substantially uniform size, shape and weight. Typically, a batch of items must fulfill requirements defined by a contract between a delivering and a receiving part, and often, number of items and minimum weight of the batch are key issues. Normally, the part of the batch that exceeds the minimum weight is considered by the delivering part as a loss and is often referred to as “giveaway”, “overweight” or “overpack”.
Typically, batches are formed by weighing the items individually, e.g. as they are moved by a conveyer system across a dynamic scale. In a computer system, the weight of each item is compared, with weights of a plurality of receptacles, e.g. bins wherein batches are formed. Often, the computer system uses statistical algorithms for assigning specific items to specific bins under consideration of required minimum weight of the batch and a desire not to produce batches with more overweight, i.e. giveaway, than required under the present conditions, i.e. given the weights of the items and the required minimum weight of the batches. The problem with prior art methods such as the one disclosed in WO 01/27567 is that global characteristics are defined for all the items to be batched, where the user determines these characteristics before the batching is initiated.
Evidently, there is a correlation between the amount of giveaway, the required minimum weight of the batches, and the weight distribution of the items being batched. In general, the larger the items are and the smaller the batches are, the more giveaway is expected.
As previously discussed, conventional batching methods are used to batch items into batches of fixed weight and item count. As an example the goal might be to make batches weighing 300 grams and exactly 3 items. In this case there is a fixed relationship between the average item weight and the average batch weight. Therefore, the overweight is simply the difference between the item count times the average item weight and the minimum allowable batch weight.